Field of the Invention
The invention concerns a method for producing a magnetic resonance image data set of a patient, for display, which quantitatively contains parameters of the protons underlying the detected magnetic resonance signal in the measured voxels. The invention also concerns a computer and a storage medium encoded with programming instructions for implementing such a method.
Description of the Prior Art
Magnetic resonance imaging has become an established investigation modality, in particular in medical diagnosis. This examination method modality is advantageous due to the high soft tissue contrast that can be achieved. In clinical imaging, magnetic resonance scans usually provide only a qualitative contrast, because magnetic resonance data of the individual voxels are subject to many influences. Although some of these influences can be controlled by the user, for example, inserting the recording parameters of the magnetic resonance protocol, in particular echo time, repetition time, bandwidth and the like, there are also factors that cannot be influenced by the user, for example coil sensitivities, software versions, as well as the type of magnetic resonance device and its manufacturer.
Since quantitative magnetic resonance data are desirable for a multiplicity of applications, methods were known for describing the parameters of protons in the measured voxels from which the magnetic resonance signals originate. Such “genuine” physical parameters are, for example, T1 relaxation time, T2 relaxation time, deviations from the homogeneity of the basic magnetic field (“off resonances”), proton densities and the like. One quantitative magnetic resonance measurement method of note is so-called magnetic resonance fingerprinting, which is described in an article by Dan Ma et al., “Magnetic Resonance Fingerprinting”, Nature, 2013, 495 (7440), pages 187-192. There the production of a large number of images, for example 1000 to 5000 images, is proposed by pseudorandomized processes of different recording parameters, in particular of the flip angle, the repetition time, the echo time and the inversion time. From this a specific signal path, which is described as a “fingerprint”, can be produced pixel-by-pixel and this can, in turn, be assigned one-to-one to a specific n-tuple of physical values (parameters) with the use of a database so that in particular it is also possible to identify individual substances, for example cerebral spinal fluid (CSF), gray cerebral matter and the like.
The parameters that are quantitatively present in such magnetic resonance data may be displayed, for example, as so-called “maps”, such as a T1 map, T2 map and the like. A problem with such a display, however, is that such quantitative magnetic resonance maps are unfamiliar for the radiologist who creates the findings, because his or her experience in diagnosis is based on different representations. In addition, individual quantitative parameters alone are not suitable for contrasting an area of interest significantly enough in the context of other anatomical structures.